In situ construction of redox-active covalent organic frameworks/carbon nanotube composites as anodes for lithium-ion batteries

Abstract

Covalent–organic frameworks (COFs) with reversible redox-active sites showed great potential application in constructing electrode materials of lithium-ion batteries (LIBs), whereas their further application is largely restricted by the poor electronic conductivity and sluggish lithium diffusion kinetics. Herein, a new redox-active COF was synthesized and further in situ grown on the carbon nanotubes (CNTs) with different COF thicknesses as the anode for LIBs. Compared with bulk COFs, COF@CNT composites can provide more exposed and accessible redox-active sites, which is beneficial for obtaining fast Li⁺ diffusion kinetics and the corresponding large capacity. The experimental results demonstrated that COF@CNT composite based anodes achieved a quite good capacity and their capacity can be further enhanced by using COF@CNT with a higher CNT content. The few-layered structure of COF@CNT-2 exhibits larger reversible capacities of 570 mA h g⁻¹ after 100 cycles at 0.1 A g⁻¹ and 373 mA h g⁻¹ after 2000 cycles at 1 A g⁻¹, which is comparable to most previously reported COF electrodes.